PPG Industries Inc. on Thursday said it fired its controller and has delayed filing its quarterly earnings report amid an internal investigation of accounting irregularities at the paint giant.

Pittsburgh-based PPG, one of the world’s largest paint and coatings makers, said it had evidence that some of its employees had made improper accounting entries at the direction of the company’s now-former controller. As a result, PPG said its financial reports for 2017 “should no longer be relied upon.”